3,819 research outputs found
Knight shift detection using gate-induced decoupling of the hyperfine interaction in quantum Hall edge channels
A method for the observation of the Knight shift in nanometer-scale region in
semiconductors is developed using resistively detected nuclear magnetic
resonance (RDNMR) technique in quantum Hall edge channels. Using a gate-induced
decoupling of the hyperfine interaction between electron and nuclear spins, we
obtain the RDNMR spectra with or without the electron-nuclear spin coupling. By
a comparison of these two spectra, the values of the Knight shift can be given
for the nuclear spins polarized dynamically in the region between the relevant
edge channels in a single two-dimensional electron system, indicating that this
method has a very high sensitivity compared to a conventional NMR technique.Comment: 4 pages, 4 figures, to appear in Applied Physics Letter
Stripe Formation in Fermionic Atoms on 2-D Optical Lattice inside a Box Trap: DMRG Studies for Repulsive Hubbard Model with Open Boundary Condition
We suggest that box shape trap enables to observe intrinsic properties of the
repulsive Hubbard model in a fixed doping in contrast to the harmonic trap
bringing about spatial variations of atom density profiles. In order to predict
atomic density profile under the box trap, we apply the directly-extended
density-matrix renormalization group method to 4-leg repulsive Hubbard model
with the open boundary condition. Consequently, we find that stripe formation
is universal in a low hole doping range and the stripe sensitively changes its
structure with variations of and the doping rate. A remarkable change is
that a stripe formed by a hole pair turns to one by a bi-hole pair when
entering a limited strong range. Furthermore, a systematic calculation
reveals that the Hubbard model shows a change from the stripe to the Friedel
like oscillation with increasing the doping rate
Voltage-biased I-V characteristics in the multi-Josephson junction model of high T superconductor
By use of the multi-Josephson junction model, we investigate voltage-biased
I-V characteristics. Differently from the case of the single junction, I-V
characteristics show a complicated behavior due to inter-layer couplings among
superconducting phase differences mediated by the charging effect. We show that
there exist three characteristic regions, which are identified by jumps and
cusps in the I-V curve. In the low voltage region, the total current is
periodic with trigonometric functional increases and rapid drops. Then a kind
of chaotic region is followed. Above certain voltage, the total current behaves
with a simple harmonic oscillation and the I-V characteristics form a
multi-branch structure as in the current-biased case. The above behavior is the
result of the inter-layer coupling, and may be used to confirm the inter-layer
coupling mechanism of the formation of hysteresis branches.Comment: 12 pages, Latex, 4 figure
Gate-controlled nuclear magnetic resonance in an AlGaAs/GaAs quantum Hall device
We study the resistively detected nuclear magnetic resonance (NMR) in an
AlGaAs/GaAs quantum Hall device with a side gate. The strength of the hyperfine
interaction between electron and nuclear spins is modulated by tuning a
position of the two-dimensional electron systems with respect to the polarized
nuclear spins using the side-gate voltages. The NMR frequency is systematically
controlled by the gate-tuned technique in a semiconductor device.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let
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